The present invention relates to methods for low-efficiency-encoding and -decoding and transmitting two types of image signals which have different resolution or progressive scanning signals, and methods for recording and reproducing these signals on and from an optical disc, as well as apparatuses for realizing these methods.
At present MPEG2 is standardized as a method for applying high-efficiency-encoding TV signals. MPEG2 is characterized in that it enables high-image-quality recording and transmission at a relatively low data rate and in that it enables compression to various data rates. One method according to MPEG2 executes encoding and decoding using the correlationship between high-resolution signals and low-resolution signals.
This encoding method executes encoding by detecting motion vectors using as a reference frame a high-resolution image or an image obtained by increasing the resolution of an image obtained by encoding and decoding a low-resolution signal. The above decoding method executes decoding with applying motion compensation using as a reference frame both a decoded high-resolution image and an image obtained by increasing the resolution of a decoded low-resolution image.
According to such conventional encoding and decoding methods, if the reference image for the motion vector is changed from a low-resolution signal to an up-convert image, the motion vector becomes less accurate. In addition, since a high-resolution signal is directly encoded, the data rate increases during encoding. In addition, due to the complexity of the encoding method, the decoding method is also complicated, resulting in the need to increase the size of a circuit for realizing both methods.
MPEG2 also defines a method for transmitting a signal obtained by encoding a high-resolution signal using the correlationship between this signal and a low-resolution signal. This method multiplexes a high-resolution signal and a low-resolution signal which have been low-efficiency-encoded before transmitting these signals.
According to a transmission apparatus for realizing such a conventional transmission method, if the broadcasting of high-resolution signals is started, viewers having a conventional decoder compatible with low-resolution signals cannot view the broadcasting.
In addition, when MPEG2 encodes progressive scanning signals, it uses as an input image to encode, a 4:2:0p signal (hereafter referred to as a xe2x80x9c420p signalxe2x80x9d) that is obtained by down-sampling color difference signals of the progressive scanning signals.
On the other hand, there is another type of 4:2:0p signal defined by SMPTE294M that is a transmission standard as the 4:2:0p signal obtained by down-sampling color difference signals for progressive scanning signals. Both signals are obtained by down-sampling color difference signals of progressive scanning signals, but have different color-difference-signal sampling positions relative to a luminance signal. Thus, to use MPEG2 to encode a 420p signal transmitted using SMPTE294M, an input signal must be up-converted to an 844 signal and then down-converted to a 420p signal of the phase of a color difference signal according to the MPEG standard, followed by MPEG compression. On the contrary, to use SMPTE294M to decode and transmit a 4:2:0p signal that has been MPEG2-compressed, a decoded signal must be up-converted to an 844 signal and then down-converted to a 420p signal of the phase of a color difference signal according to the SMPTE294M standard, followed by transmission.
According to such conventional image-signal encoding, decoding, and transmission methods and apparatuses using these methods, a color difference signal is converted twice between the apparatuses and may thus be degraded.
In addition, data encoded using the MPEG2 method is recorded on an optical disc for dense recording that is called a digital video disc (hereafter referred to as a xe2x80x9cDVDxe2x80x9d). At present, only NTSC- or PAL-based image signals that are interlaced scanning signals are recorded on a DVD, and progressive scanning signals that are image signals having more vertical scanning lines than the NTSC- or PAL-based signals have not been put to practical use yet.
When progressive scanning signals encoded using MPEG2 are recorded on a conventional optical disc, twice as many pixels as in interlaced scanning signals are required to force the data rate of a resulting bit stream to be increased. Such a high data rate may not be dealt with by the existing optical-disc standards. In addition, commercially available apparatuses cannot decode (playback) progressive image signals that have been recorded on an optical disc within a single stream, and this is inconvenient to users.
It is an object of this invention to provide an encoding apparatus for accurately determining motion vectors to encode two types of image signals of different resolutions and a decoding apparatus for decoding signals encoded by the encoding apparatus.
To achieve the above-mentioned object, the present invention is an image signal encoding apparatus comprising
a motion vector detecting means for detecting motion vectors using a first image signal of a high resolution, a resolution reducing means for creating a second image signal of a low resolution from said first image signal, an image signal interpolating means for interpolating said second image signal in such a way as to have the same number of pixels as said first image signal, thereby creating an interpolated signal, a differential means for determining the differential between said first image signal and said interpolated signal to create a differential signal, and
an encoding means for using said motion vectors to low-efficiency-encode said differential signal.
Further, the present invention is an image signal encoding apparatus comprising, a motion vector detecting means for detecting motion vectors using a first image signal of a high resolution, a resolution reducing means for creating a second image signal of a low resolution from said first image signal, a second encoding means for encoding said second image signal to create a second encoded signal, a second decoding means for decoding said second encoded signal to create a second decoded signal, an image signal interpolating means for interpolating said second decoded signal in such a way as to have the same number of pixels as said first image signal, thereby creating an interpolated signal, a differential means for determining the differential between said first image signal and said interpolated signal to create a differential signal, and a first encoding means for using said motion vectors to low-efficiency-encode said differential signal.
This configuration can accurately determine motion vectors and reduce the data rate after encoding by encoding differential signals.
Further, the present invention is an image signal decoding apparatus comprising a first decoding means for decoding a first stream obtained by encoding a high-resolution signal to obtain a first image signal, a second decoding means for decoding a second stream obtained by encoding a low-resolution signal to obtain a second image signal, an image signal interpolating means for interpolating said second image signal in such a way as to have the same number of pixels as said first image signal, thereby creating an interpolated signal, and an adding means for adding said first image signal and said interpolated signal to create a decoded signal for said high-resolution signal.
This configuration can use a simple circuit configuration to provide a decoding apparatus for signals encoded by the present encoding apparatus.
It is also an object of this invention to provide an image-signal transmission apparatus that enables viewers having a decoder for low-resolution signals to view broadcasting.
To achieve the above-mentioned object, the present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, and a transmission means for transmitting said first and second encoded signals through a first and a second channels respectively that are different from each other.
This configuration transmits two types of signals of low and high resolutions to enable viewers having a decoder exclusively used for low-resolution signals to view broadcasting.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal,
a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, a synchronizing-signal adding means for adding to said first and second encoded signals, a synchronizing signal that frame-synchronizes said first encoded signal with said second encoded signal in order to obtain a first and a second synchronized signals, and a transmission means for transmitting said first and second synchronized signals through a first and a second channels respectively that are different from each other.
This configuration transmits two types of signals of low and high resolutions to enable viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and enables the low- and high-resolution signals to be simply synchronized.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal,
a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, a billing information adding means for adding billing information to said second encoded signal to obtain a billed signal, and a transmission means for transmitting said first encoded signal and said billed signal through a first and a second channels respectively that are different from each other.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and can impose a fee on only those viewers who receive high-resolution signals.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, an encryption means for encrypting said second encoded signal to create an encrypted signal, and a transmission means for transmitting said first encoded signal and said encrypted signal through a first and a second channels respectively that are different from each other.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and can more efficiently compress signals the resolution of which is to be increased.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, and a transmission means operative when transmitting said first and second encoded signals using a first and a second channels respectively that are different from each other, for transmitting said second encoded signal prior to said first encoded signal, said first and second encoded signals corresponding to the same frame of said input image signal.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and eliminates time loss during broadcasting caused by the decoding of high-resolution signals.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, a first error correction information adding means for adding error correction information to said first encoded signal, a second error correction information adding means for adding error correction information to said second encoded signal, and a transmission means for transmitting through a first channel the first encoded signal with said error correction information added thereto while transmitting through a data transmitting channel the second encoded signal with said error correction information added thereto, wherein less error correction information is added to said second encoded signal than the other data transmitted through said data transmitting channel.
This configuration transmits two types of signals of low and high resolutions to enable viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and can more efficiently encode signals the resolution of which is to be increased.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, and a transmission means for transmitting said first and second encoded signals through a first and a second channels, respectively, and transmitting through said first and second channels an audio signal synchronizing with said input image signal.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and enables only audio signals to be broadcasted if low-resolution signals cannot be decoded.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, and a transmission means operative when transmitting said first and second encoded signals through a first and a second channels, respectively, for transmitting only through said first channel an audio signal synchronizing with said input image signal.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting, enables only audio signals to be broadcasted if low-resolution signals cannot be decoded, and can improve the encoding efficiency for signals the resolution of which is to be increased. This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and enables viewers who can receive high-resolution signals to use acoustic effects.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, and a transmission means operative when transmitting said first and second encoded signals through a first and a second channels, respectively, for transmitting through said first channel an audio signal synchronizing with said input image signal while transmitting through the second channel a signal related to said audio signal.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting. For viewers having a decoder compatible with high-resolution signals, even if a broadcasting source provides only low-resolution signals, this configuration can improve the image quality of the low-resolution signals.
The present invention is an image signal transmission apparatus comprising a determining means for receiving an input image signal and determining whether the input image signal has a high or low resolution, a first dividing means operative when the result of the determination by the determining means is for a high resolution, for dividing said input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal and the third image signal described below to obtain a first encoded signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, a second dividing means operative when the result of the determination by the determining means is for a low resolution, for dividing said input image signal into a third image signal and a fourth image signal that is the differential between said input image signal and said third image signal or between said input image signal and an encoded/decoded signal of said third image signal, a third encoding means for low-efficiency-encoding said fourth image signal to obtain a third encoded signal, and a transmission means for transmitting said first encoded signal through a first channel while transmitting said second and third encoded signals through a second channel.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting, and can improve the image quality of a high-resolution mode.
The present invention is an image signal transmission apparatus comprising a conversion encoding means for converting an input image signal into a first image signal of a low resolution and low-efficiency-encoding it to obtain a first encoded signal, a reverse-conversion decoding means for decoding and reversely converting said first encoded signal to obtain a decoded signal having the same resolution as said input image signal, a differential-image creating means for determining the differential between said decoded signal and said input image signal to create a second image signal, a second encoding means for low-efficiency-encoding said second image signal to obtain a second encoded signal, and a transmission means for transmitting said first encoded signal through a first channel while transmitting the second encoded signal through a second channel.
This configuration enables viewers having a decoder exclusively used for low-resolution signals to view broadcasting.
The present invention is an image signal transmission apparatus comprising a dividing means for dividing an input image signal into a first image signal of a low resolution and a second image signal that can obtain the same resolution as said input image signal when combined with said first image signal, a first encoding means for low-efficiency-encoding said first image signal to obtain a first encoded signal, a differential creating means for decoding said first encoded signal and determining the differential between this signal and said first image signal to determine a differential image signal, a second encoding means for low-efficiency-encoding said differential image signal to obtain a second encoded signal, a third encoding means for low-efficiency-encoding said second image signal to obtain a third encoded signal, and a transmission means for transmitting said first encoded signal through a first channel while transmitting said second and third encoded signals through a second channel.
For viewers having a decoder compatible with high-resolution signals, even if a broadcasting source provides only low-resolution signals, this configuration can improve the image quality of the low-resolution signals, thereby improving the image quality of the high-resolution signals.
It is another object of this invention to provide an image-signal transmission method and apparatus, an image-signal encoding method and apparatus, and an image-signal decoding method and apparatus that can reduce the degradation of the image quality of color difference signals for progressive scanning signals used to improve the efficiency in encoding and decoding.
The present invention is an image signal transmission method wherein progressive scanning signals are transmitted which include information indicating the sample position of a color difference signal relative to a luminance signal.
Further, the present invention is an image signal transmission apparatus including a conversion means for using digitalized progressive scanning signals as an input signal to convert both the phase of a color difference signal in said input signal and the number of samples or only the number of samples, and a multiplexing means for multiplexing together an output signal from said conversion means and information indicating the sample position of the color difference signal after conversion by said conversion means.
When a transmitted signal is to be low-efficiency-encoded, this configuration enables a color difference signal to be converted appropriately based on information indicating the sample position of the color difference signal in order to avoid the unwanted degradation of the color difference signal. This configuration also enables a plurality of image signals to be transmitted over the same transmission path.
The present invention is an image signal transmission apparatus comprising a color difference information reading means for using as an input signal, digitalized progressive scanning signals that are multiplexed with information indicating the sample position of a color difference signal in order to read the information indicating the sample position of said color difference signal which is multiplexed in said input signal, and a conversion means for converting both the phase of the color difference signal in said input signal and the number of samples or only the number of samples depending on said information read by said color difference information reading means.
This configuration converts both the phase of a color difference signal in an input signal and the number of samples, or only the number of samples to enable the color difference signal to be converted appropriately depending on information read by the color difference information reading means, thereby avoiding the unwanted degradation of the color difference signal.
Further, the present invention is an image signal encoding method wherein a low-efficiency-encoded image signal is multiplexed with information indicating the sample position of a color difference signal relative to a luminance signal.
When low-bit-rate-encoded data is to be decoded, this configuration avoids the unwanted degradation of a color difference signal caused by an error in conversion in order to enable a plurality of types of signals to be encoded by the same encoder.
The present invention is an image signal encoding apparatus comprising a conversion means for using digitalized progressive scanning signals as an input signal to convert both the phase of a color difference signal in said input signal and the number of samples or only the number of samples, an encoding means for low-efficiency-encoding an output signal from said conversion means, and a multiplexing means for multiplexing together the output from said encoding means and information indicating the sample position of the color difference signal after conversion by said conversion means.
This configuration multiplexes an encoded signal and information indicating the sample position of a color difference signal after conversion to enable appropriate conversion during decoding in order to prevent the unwanted degradation in image quality of the color difference signal.
The present invention is an image signal decoding apparatus comprising a decoding means for using as an input signal, low-efficiency-encoded progressive scanning signals that are multiplexed with information indicating the sample position of a color difference signal in order to low-efficiency-decode said input signal, a color difference information reading means for reading the information indicating the sample position of said color difference signal which is multiplexed in said input signal, and a conversion means for converting both the phase of the color difference signal in an output signal of said decoding means and the number of samples or only the number of samples depending on said information read by said color difference information reading means.
This configuration converts both the phase of a color difference signal of a decoded signal and the number of samples, or only the number of samples to enable the color difference signal to be converted appropriately depending on information on the sample position of a read color difference signal, thereby reducing the unwanted degradation in image quality of the color difference signal.
The present invention is an image signal encoding apparatus comprising an encoding means for using as an input signal, digitalized progressive scanning signals that are multiplexed with information indicating the sample position of a color difference signal in order to low-efficiency-encode said input signal, a color difference information reading means for reading the information indicating the sample position of said color difference signal which is multiplexed in said input signal, and a multiplexing means for multiplexing together the output from said encoding means and the information read by said color difference information reading means.
This configuration multiplexes an encoded signal and information on the sample position of a read color difference signal to enable compression without the duplicate application of a color filter in order to reduce the degradation in image quality of the color difference signal.
The present invention is an image signal decoding apparatus comprising a decoding means for using as an input signal, low-efficiency-encoded progressive scanning signals that are multiplexed with information indicating the sample position of a color difference signal in order to low-efficiency-decode said input signal, a color difference information reading means for reading the information indicating the sample position of said color difference signal which is multiplexed in said input signal, and a multiplexing means for multiplexing together the output from said decoding means and the information read by said color difference information reading means.
This configuration multiplexes a decoded signal and information on the sample position of a read color difference signal to enable the phase of a color difference signal in an output signal to be determined during decoding, thereby multiplexing the output signal and information on the sample position of the color difference signal so as to enable the color difference signal to be converted appropriately.
The present invention is an image signal encoding apparatus comprising a conversion means for using digitalized progressive scanning signals as an input signal to convert both the phase of a color difference signal in said input signal and the number of samples or not to convert them depending on said input signal, an encoding means for low-efficiency-encoding an output signal from said conversion means, and a multiplexing means for multiplexing together the output from said encoding means and information indicating the sample position of the color difference signal in the output signal from said conversion means.
This configuration can multiplex an encoded signal and information indicating the sample position of a color difference signal in an input signal in order to enable compression without the duplicate application of a color filter, thereby preventing the unwanted degradation in image quality of the color difference signal.
The present invention is an image signal decoding apparatus comprising a decoding means for using as an input signal, low-efficiency-encoded progressive scanning signals that are multiplexed with information indicating the sample position of a color difference signal in order to low-efficiency-decode said input signal, a color difference information reading means for reading the information indicating the sample position of said color difference signal which is multiplexed in said input signal, and a conversion means for converting both the phase of the color difference signal in respect to said output signal of said decoding means and the number of samples or not to convert them depending on said information read by said color difference information reading means.
This configuration converts or does not convert the phase of the color difference signal relative to an output signal and the number of samples depending on information on the sample position of a read color difference signal to enable the color difference signal to be processed appropriately, thereby reducing the degradation of the image quality.
It is yet another object of this invention to provide an optical disc recording method compatible with progressive image signals without substantially changing conventional apparatuses.
The present invention is an optical-disc recording method comprising dividing for each frame a progressive image signal at a frame rate N (N is a positive real number indicating the number of frames per second) into two progressive image signals at a frame rate smaller than N, compressively encoding each of the two divided progressive signals to obtain two bit streams, and recording said two bit streams on different recording layers of an optical disc.
This configuration enables conventional compressive encoding for interlaced image signals to be directly used or allows progressive image signals to be directly compressed, thereby preventing the encoding efficiency from decreasing due to division.
It is yet another object of this invention to provide an optical disc reproduction method compatible with progressive image signals without substantially changing conventional apparatuses.
The present invention is an optical disc reproduction method comprising reproducing two bit streams from each of different recording layers of the optical disc on which two progressive image signals at a frame rate smaller than N obtained by dividing a progressive image signal at a frame rate N (N is a positive real number indicating the number of frames per second) are each recorded as the compressively encoded bit stream; extensionally decoding the bit streams to obtain two progressive image signals at said frame rate smaller than N, synthesizing the two progressive image signals for each frame, and outputting a progressive image signal at said frame rate N.
This configuration provides an apparatus that uses conventional extensional decoding means for interlaced image signals to playback an optical disc for progressive image signals.
The present invention is an optical disc reproduction method for reproducing an optical disc on which two progressive image signals at a frame rate smaller than N obtained by dividing a progressive image signal at a frame rate N (N is a positive real number indicating the number of frames per second) are each recorded a compressively encoded bit stream, wherein the method comprises reproducing only one recording layer to obtain a bit stream, extensionally decoding the bit stream, and outputting it as a progressive image signal at said frame rate smaller than N.
This configuration enables conventional extensional decoding means for interlaced image signals to be directly used to playback progressive image signals of a frame rate N/2.